Fixed diffing bug where item's parentID wasn't taken into account. Moving items would otherwise remain broken.

Reload parent items when removing / inserting

Author: guidedways

Sources/DiffableDataSourceSnapshot.swift

@@ -302,12 +302,13 @@ extension DiffableDataSourceSnapshot {
 
     /// Only IDs should be equal.
     static func == (lhs: Self, rhs: Self) -> Bool {
-      lhs.itemId == rhs.itemId
+      lhs.itemId == rhs.itemId && lhs.parentId == rhs.parentId
     }
 
     /// Only ID means as hash.
     func hash(into hasher: inout Hasher) {
       hasher.combine(itemId)
+      hasher.combine(parentId)
     }
   }
 

Sources/OutlineViewDiffableDataSource.swift

@@ -280,15 +280,23 @@ public extension OutlineViewDiffableDataSource {
               // Insert outline view item
               let insertionIndexes = IndexSet(integer: inserted.itemPath.last.unsafelyUnwrapped)
               let parentItem = inserted.parentId.flatMap(newSnapshot.itemForId)
+             
               outlineView?.insertItems(at: insertionIndexes, inParent: parentItem, withAnimation: [.effectFade, .slideDown])
+              
+              // Reload new parent so their expansion states can be reloaded
+              outlineView?.reloadItem(parentItem, reloadChildren: true)
             }
 
           case .remove(_, let before, let indexAfter):
             if indexAfter == nil {
               // Delete outline view item
               let deletionIndexes = IndexSet(integer: before.itemPath.last.unsafelyUnwrapped)
               let oldParentItem = before.parentId.flatMap(oldSnapshot.itemForId)
-              outlineView?.removeItems(at: deletionIndexes, inParent: oldParentItem, withAnimation: [.effectFade, .slideUp])
+              
+              outlineView?.removeItems(at: deletionIndexes, inParent: oldParentItem, withAnimation: [.effectFade, .slideDown])
+              
+              // Reload old parent so their expansion states can be reloaded
+              outlineView?.reloadItem(oldParentItem, reloadChildren: true)
             }
             else {
               // the item moved since it's got a valid "index after". We handle moves in `.insert` so this can be